Downshift Tuning

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Downshift Tuning

Post by Buickv6 »

Hi,

I am new here in this forum and new to MS. I have an MS3 with MS3X and a msgpio communicating thru can running mshift. Both these were diy kits purchased from DIY Auto Tune that I assembled myself. The MS3 is running a 231ci buick v6 and the gpio a 4L60e auto box. Both are running in the car now and i am currently trying to get the gearbox shifting the way i would like it. I know that my shift tables are not yet perfect but if someone would be able to help me i need some help with the downshifting behaviour of the box. When decelerating it seems to change back down the gears all the way to first even though the road speed is still too high for first gear i.e. it should be in second gear instead. When i re-apply the accelerator the engine rpm climbs rapidly as though the trans is in neutral and then changes to a higher or more appropriate gear for the load and speed. It maybe a setting I have missed or entered incorrectly but i cannot see it at this time, so if someone could take a look at my tune and log file and give me some pointers it would be appreciated. I am using Tunerstudio v2.6.19 with MS3 format 0435.16 and v5.101 mshift.
Below are my tune and log files. I had to compress my logs files as they are all too large. At 404.000 in the log you can see that the box changes back to first even though the speed is about 75kph. Hope you can view what i am experiencing with the downshifts.

Thanks
Attachments
2015-06-17_19.43.10.zip
(462.81 KiB) Downloaded 222 times
Current VR Tune_21.13.41.msq
(212.36 KiB) Downloaded 409 times
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Downshift Tuning

Post by Bernard Fife »

BuickV6,

We need the MShift .MSQ settings file to be able to comment properly (it appears that you have posted the msextra engine MSQ).

In general, there are a number of reasons that what you are seeing could happen:
- the shifts are based on the average load, not the instant load, so you need to take that into account when viewing your shift table,
- if the rev limiting is set up, you might be under the lower limit so the trans will downshift,
- if the manual gear lever position is 'flaky' it can cause all sorts of shift issues,
- if the gear shift table is not tuned properly,
- etc., etc.

At 404 in your log, it looks like you are just on the border between 1st and 2 in your shift table (which I haven't seen, but it looks like that from the way the target gear (tGear) is behaving). So you might want to revise the area of the shift table around 80 mph and less than 28 kPa by changing any 1 there to a 2.

You are also under 1100 rpm at 404 seconds in the log. If the lower limit of the rpm limiting is above this (and rpm limiting is enabled), then you need to lower that limit even more (t perhaps 900 rpm?).

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Re: Downshift Tuning

Post by Buickv6 »

Lance,

Sorry this should be the msq i should have posted.
Attachments
Mshift_CurrentTune.msq
(57.49 KiB) Downloaded 351 times
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Re: Downshift Tuning

Post by Buickv6 »

Lance,

At 409.727 the log shows that the current gear is 1. The average load (mshift) is 27.7 and the rpm is 1074.0 while the speed is 81.8 kph. Looking at my shift table 1 @ 30 kpa load and at 80 kph the transmission should still be in 4th gear, or am i reading the table wrong?
I do have rev limiting set up and the lower limit is set to 1000 rpm so it should not be under the lower limit at this point but i can lower that to 900 rpm as you suggest.
I do not have error checking enabled so i will enable that to check for lever errors and get another log.

Cheers
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Downshift Tuning

Post by Bernard Fife »

BuickV6,

Thanks for all the excellent info. I can replicate exactly what you are seeing on my bench, so something is definitely not right in the code. I will look into this an post back here when I have t fixed.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Downshift Tuning

Post by Bernard Fife »

BuickV6,

Okay, I *think* I have found and fixed the problem in the attached 5.101ii code (and the required 5.101i INI). Hopefully it will work properly for you (it appears to solve the issue you have spotted, on my bench at least).
Monitor_5101ii.abs.s19
Target gear lookup fix
(83.91 KiB) Downloaded 288 times
GPIO_MShift_5101i.ini
DO NOT USE THIS INI.
USE THE ONE IN THE POST BELOW.
SEE POSTS FOR REASON.
(292.11 KiB) Downloaded 256 times
Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Re: Downshift Tuning

Post by Buickv6 »

Lance,

Thanks for that i will load the new code and ini file and use it in the car tonight and let you know how it goes.
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Re: Downshift Tuning

Post by Buickv6 »

Lance,

Loaded the new code to the gpio and then went to load the ini file and i get the following message -

A problem was encountered loading the project mshift : Reported error, invalid ini row in loaded ini (turbo baud), root problem:0
Buickv6
Posts: 12
Joined: Wed Jun 17, 2015 12:55 am

Re: Downshift Tuning

Post by Buickv6 »

Lance,

Here is a screenshot of the error
Attachments
Error loading ECUconfiguration.pdf
(222.55 KiB) Downloaded 231 times
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Downshift Tuning

Post by Bernard Fife »

BuickV6,

Sorry about that! Apparently some others have seen that issue too. For example, Addicted here: viewtopic.php?f=4&t=973&start=10#p5351 He was able to fix the issue by "simply copying the ini into the projectcfg and renaming it to CAN1.ini worked perfectly".

However, I *thought* I had fixed this (later in that thread) and I obviously forgot to replace my 'official' copy with the edited version. I'll attach that here (renamed as GPIO_MShift_5101ii.ini):
GPIO_MShift_5101ii.ini
(292.18 KiB) Downloaded 235 times
Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
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